Magnesium modification of a calcium phosphate cement alters bone marrow stromal cell behavior via an integrin-mediated mechanism

The chemical composition, structure and surface characteristics of biomaterials/scaffold can affect the adsorption of proteins, and this in turn influences the subsequent cellular response and tissue regeneration. With magnesium/calcium phosphate cements (MCPC) as model, the effects of magnesium (Mg) on the initial adhesion and osteogenic differentiation of bone marrow stromal cells (BMSCs) as well as the underlying mechanism were investigated. A series of MCPCs with different magnesium phosphate cement (MPC) content (0∼20%) in calcium phosphate cement (CPC) were synthesized. MCPCs with moderate proportion of MPC (5% and 10%, referred to as 5MCPC and 10MCPC) were found to effectively modulate the orientation of the adsorbed fibronectin (Fn) to exhibit enhanced receptor binding affinity, and to up-regulate integrin α5β1 expression of BMSCs, especially for 5MCPC. As a result, the attachment, morphology, focal adhesion formation, actin filaments assembly and osteogenic differentiation of BMSCs on 5MCPC were strongly enhanced. Further in vivo experiments confirmed that 5MCPC induced promoted osteogenesis in comparison to ot her CPC/MCPCs. Our results also suggested that the Mg on the underlying substrates but not the dissolved Mg ions was the main contributor to the above positive effects. Based on these results, it can be inferred that the specific interaction of Fn and integrin α5β1 had predominant effect on the MCPC-induced enhanced cellular response of BMSCs. These results provide a new strategy to regulate BMSCs adhesion and osteogenic differentiation by adjusting the Mg/Ca content and distribution in CPC, guiding the development of osteoinductive scaffolds for bone tissue regeneration.     

Influence of Fine Grains on the Bending Fatigue Behavior of Two Implant Titanium Alloys

By means of the ultrasonic surface impact (amplitude of 30 μm, strike number of 48,000 times/mm²), nanograins have been achieved in the surfaces of both Ti6Al4V(TC4) and Ti3Zr2Sn3Mo25Nb(TLM) titanium alloys, mainly because of the dislocation motion. Many mechanical properties are improved, such as hardness, residual stress, and roughness. The rotating–bending fatigue limits of TC4 and TLM subjected to ultrasonic impact are improved by 13.1% and 23.7%, separately. Because of the bending fatigue behavior, which is sensitive to the surface condition, cracks usually initiate from the surface defects under high stress amplitude. By means of an ultrasonic impact tip with the size of 8 mm, most of the inner cracks present at the zone with a depth range of 100~250 μm in the high life region. The inner crack core to TC4 usually appears as a deformed long and narrow α-phase, while the cracks in TLM specimens prefer to initiate at the triple grain boundary junctions. This zone crosses the grain refined layer and the deformed coarse grain layer. With the gradient change of elastic parameters, the model shows an increase of normal stress at this zone. Combined with the loss of plasticity and toughness, it is easy to understand these fatigue behaviors.     

Magnesium lithospermate B acts against dextran sodiumsulfate-induced ulcerative colitis by inhibiting activation of the NRLP3/ASC/Caspase-1 pathway

This study aimed to observe the therapeutic effects of magnesium lithospermate B on acute and chronic colitis induced by dextran sodiumsulfate (DSS) and the role of inflammasome complex (NOD-like receptor protein, NLRP; apoptosis-associated speck-like protein containing, ASC; caspase-1). Establishment of acute and chronic colitis models were by using 5% DSS oral administration in BALB/C male mice. Magnesium lithospermate B (240 mg/kg body weight) was given by subcutaneous injection. Samples were collected for biomarker assay, histological examination, immunohistochemical evaluation and western blot. There was obvious increase in TNF-α level and NLPR3, ASC, and caspase-1 expressions in acute and chronic colitis groups compared with the normal control. Significant decrease of the tumor necrosis factor-α level and the expressions of NLPR3, ASC, and caspase-1 were observed after treatment with magnesium lithospermate B. This study showed that magnesium lithospermate B could be used to treat acute and chronic colitis by inhibiting the activation of the NLRP3/ASC/Caspase-1 pathway.     

镓合金用于牙体修复的临床应用研究

目的：观察镓合金作为一种新型的牙体修复材料在临床中的使用情况。方法：对48个牙体充填后经过6月、9月、12月、24月随访观察。结果：48个修复体中Ⅰ类洞40个、Ⅱ类洞6个、Ⅴ类洞2个，除4个修复体因充填后牙尖折断及乳牙替换而脱落，其余修复体均完整，无边缘折断或裂缝。优良率达95．5％。失败率4．5％。结论：镓合金对口腔黏膜及牙龈组织无刺激，无毒，无过敏反应，不污染环境，是一种良好的牙体修复材料。     

镍钛形状记忆合金环抱接骨板治疗桡骨近端1/3骨折

目的探讨治疗桡骨近端1/3骨折的理想内固定方法.方法 2001年8月～2004年4月,采用镍钛形状记忆合金环抱接骨板治疗24例桡骨近端1/3骨折.其中男19例,女5例.年龄16～48岁.摔伤9例,压砸伤5例,交通事故伤4例,直接暴力撞击伤3例,高处坠落伤3例.按照形状记忆合金环抱接骨板的安装方法进行骨折复位内固定.术后定期随访,观察骨折愈合及功能恢复情况.结果所有患者均获随访4～21个月,平均10个月.均无术中、术后并发症,切口Ⅰ期愈合;X 线片示骨折均于术后8～12周临床愈合,根据Anderson疗效标准,功能恢复优18例,良5例,可1例,优良率95.83%.结论应用镍钛形状记忆合金环抱接骨板治疗桡骨近端1/3骨折具有创伤小、操作简便安全、固定可靠、组织相容性好、并发症少等优点,有利于促进骨折愈合和肘、腕关节功能康复,是一种治疗桡骨近端1/3骨折的较好方法.     

复合矫治弓丝接头的力学性能及接头组织观察

目的　测试复合矫治弓丝接头的机械性能及分析接头、接头断口变化。方法　测试复合矫治弓丝接头的拉伸强度、剪切强度、扭转强度、弯曲形变残余角,TiNi形状记忆合金丝超弹性,扫描电镜观察及分析接头、断口组织变化。结果　复合矫治弓丝接头抗拉伸强度为32 0～36 0MPa ,剪切强度为2 2 0～2 5 0MPa ,抗扭转强度为30～4 0N·m、断裂时扭转角度不小于1 4 4 0°,弯曲形变残余角为1 2～1 7°;钎焊异质接头中TiNi形状记忆合金丝超弹性几乎没有破坏;接头钎料与TiNi形状记忆合金界面不存在扩散层,与不锈钢丝界面之间有一较宽的扩散层,接头断裂多发生在钎料与TiNi形状记忆合金超弹界面处,部分发生在钎缝中心。结论　复合矫治弓丝机械性能符合正畸临床要求,可应用于临床。     

The Effects of Zero Magnesium Dialysate and Magnesium Supplements on Ionised Calcium Concentration in Patients on Regular Dialysis Treatment

The effect of oral magnesium carbonate aluminium hydroxide onserum ionised calcium, total calcium, aluminium and magnesium,was assessed in 31 patients with chronic renal failure, duringand after one haemodialysis. The behaviour of ionised calcium and total calcium was the samein both groups. Each showed a slight fall during dialysis, whichwas not significant. Serum total calcium was 0.2–0.3 mmol/l(0.8–1.2 mg/dl) greater throughout the period of dialysisin the group taking aluminium hydroxide. Serum magnesium andaluminium were both lower in the group treated with magnesiumcarbonate. In the group taking magnesium carbonate, serum magnesium concentrationsfell markedly during dialysis, but otherwise were maintainedwithin the reference range by the use of a magnesium-free dialysate.These results show the effectiveness of magnesium carbonateoral phosphate-binding agents and zero magnesium dialysate inreducing serum aluminium without affecting the behaviour ofserum calcium fractions during dialysis.     

新型胫骨髓内钉的研制与生物力学研究

目的　研制新型胫骨串孔型髓内钉并对其进行生物力学研究。方法　用TAMZ合金制造远端锁孔由一个三个同样直径的串孔所替代的 9根新型胫骨髓内钉。将髓内钉安装在自行设计的夹具中 ,先将 3根新钉进行静态垂直压缩实验 ,根据静态实验结果 ,分别测试 6根新钉的动态疲劳强度。结果　新钉的静态压缩破坏载荷为 2 1 33N ,是人平均体重的 3倍多 ;通过 5 0万次压缩循环的条件疲劳强度为 1 2 0 0N ,约是人体重的 2倍。结论　新钉不仅能够方便临床使用 ,而且拥有较好的力学特性     

形状记忆合金环抱接骨板治疗锁骨骨折

目的 探讨形状记忆合金环抱接骨板治疗锁骨骨折的手术方法及疗效。方法 采用西脉记忆合金环抱接骨板治疗锁骨骨折54例。结果 54例病人全部获得随访，优良率96.3％。结论 形状记忆合金环抱接骨板治疗锁骨骨折是一种方便有效的方法，具有手术操作简便、内固定确实等优点，但应加强术后管理。     

2种磨牙根管预备方法的成本-效果分析

目的:比较不锈钢K锉常规根管预备(SSPT)法与镍钛机用根管器械逐步深入预备(NRPT)法在磨牙根管治疗中的近期临床效果和成本/效果(C/E)值。方法:入选患者随机分为SSPT法(49例)和NRPT法(45例)2组,记录治疗后不良反应、补救治疗措施和所花费用,评价近期疗效并进行成本-效果分析,用SPSS11.5统计分析软件进行数据统计。结果:NRPT组治疗满意率优于SSPT组(P=0.034),但前者人均治疗成本显著高于后者(P=0.001)。对重度弯曲根管,NRPT组治疗满意率优于SSPT组(P=0.007);前者的C/E值较后者低394.52元;轻中度弯曲根管前者的C/E值较后者高192.04元。根尖正常患者,NRPT组治疗满意率高于SSPT(P=0.012),但前者C/E值比后者高32.32元;而根尖阴影患者NRPT组的C/E值较SSPT组高376.47元。结论:NRPT法的疗效优于SSPT法,但治疗成本较高;对重度弯曲根管患牙,NRPT法可使患者受益;对中轻度弯曲根管患牙,应选用SSPT法。对根尖正常的患者,NRPT法近期疗效更高,而治疗前有根尖病变的患者,SSPT法可节约治疗成本。